This invention relates in general to combustion devices and in particular to a new and useful combustion device for a heater or stove.
The invention relates to a combustion chamber for heating devices operated with liquid fuel, having a combustion space with a correlated first section in which the combustion air supply occurs tangentially, and a further second section, having a pipe with the ignition means, as well as a connection for a metering pump and for an area for spark plug ventilation.
Such combustion chambers are needed for heating devices which are used as household heating systems, e.g. at cooking stations and also for motor independent vehicle heaters. For household heating systems pressure atomizer burners with wattages starting at about 20 kW are known. Smaller wattages down to 12 kW are realized with expensive oil preheating, but substantially smaller wattages are not possible. But devices with relatively low output are required when what is involved is e.g. a single cooking station. In vehicle heaters the known devices can be regulated for burner outputs between "Full" ("High") and "Off", in some vehicle heaters between "Full" and about "one-fourth burner output". A greater control range is not known at present, although it would be desirable for comfort and also so as to have to ignite only once in a heating interval, while in the known heating systems with thermostat control the control occurs by On/Off switching; this leads to increased current consumption from the vehicle battery and may lead to premature discharge of the battery, the more so as such heaters are operated preferably at standstill, that is, with the engine turned off.
In such heating devices the fuel supply occurs by means of a pulse-controlled metering pump. In this case it is possible by means of a frequency regulator, through a thermostat, to regulate the output of the heating equipment to a certain extent by varying the pump frequency, as for instance in a range of from 1:4 to about 1:8.
The invention provides a combustion chamber, by the construction and design of which its output range becomes variable, so that the control range of the heating equipment is substantially expanded. At the same time the combustion space is to be suitable for installation either with the axis vertical or with the axis horizontal.
The combustion chamber includes a first section separated from the combustion space by a plate having a central passage opening and which comprises a truncated cone-shaped portion with a cylindrical prolongation with the tapered part of the truncated cone-shaped portion pointing toward the combustion space and being provided with a pipe for tangential combustion air supply. A second section is pot-shaped and is connected at its open side with the first section and has a lateral pipe. The lateral pipe is designed to receive the spark plug ventilation line which extends from the first section to the lateral pipe of the second section. An internal diaphragm type insert is arranged in the region of the connection of the second section to the first section. With this design of the combustion chamber according to the invention an arrangement is indicated which permits an output regulation over the almost total output range. This results from the fact that both the flame form and the region in which the combustion takes place inside the combustion chamber can be varied. Thus it can be achieved that the combustion takes place only in the second section of the combustion chamber, or in both sections or in the entire combustion chamber and that thereby a controllability is obtained.
To keep the combustion in the second section and thereby to be able to run the smallest output stage, it has been found appropriate to give the diaphragm type insert a circular ring-shaped cross-section, the outer edge being bent by about 90.degree. to form an abutment edge and the inner edge by about 90.degree. in the opposite direction.
The exact angle measurements depend on the installation situation.
For the transition combustion from the second to the first section the diameter of the passage opening is of importance. Appropriately the ratio of the inner diameter to the outer diameter of the diaphragm type insert is 1:1.2 to 1:4, preferably 1:2. To protect this diaphragm type insert against overbearing, according to further aspect of the invention, there is arranged below the insert an anti-overheating disc which has a circular ring-shaped cross-section and is bent at its inner edge by about 90.degree. to form an abutment flange. The anti-overheating disc is adapted to apply by its bent abutment flange against the bent inner edge of the diaphragm type insert, the disc being spaced from the insert and having a somewhat smaller outside diameter than the inner diameter of the second section.
For the form of the hot combustion gases or of the flame passing from the second section via the first section into the combustion chamber, the matching of the exit openings is essential. A further feature of the invention therefore is that the side of the plate toward the combustion space has a surface ascending from about the inner edge to a flange forming horizontal section at the outer edge. Thereby a flame form from dish-shaped to ray-shaped can be adjusted. Advantageously, the angle of inclination of the ascending surface is between 15.degree. and 90.degree., preferably 20.degree..
For the connection of the combustion chamber wall and possibly also of a heat component it is appropriate to provide contiguous to the ascending surface of the plate on both sides a plane section, and according to a variant, the plate is formed in its plane inner section to receive a flame guiding insert. According to the invention, the ascending surface may be concave, this leading to an especially good contact of the combustion gases or of the flame. The further sub-claims indicate appropriate realizations of the flame guiding insert. This flame guiding insert contributes essentially to the flame form.
Accordingly it is an object of the invention to provide an improved combustion device which includes a plate having an opening which communicates with the top of a combustion housing having an upper portion with a tangential combustion air inlet and a lower portion for ignition of the burnable products which is connected with a lateral pipe containing a spark plug igniter and a fuel supply into the pipe along with a recirculating passage extending from the upper combustion passage back to the ignition and fuel supply plate which connects into the ignition portion of the combustion chamber.
A further object of the invention is to provide an improved device which may function as a heater or cooker.
A further object of the invention is to provide a combustion device which is simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.